Fluid operated actuators have received great success, in part, because of their wide range of applicability. One example of a fluid operated actuator is a piston positioned in a cylinder. The piston may be attached to a working carriage extending through a sealed portion of the cylinder that is attached to the piston. Another example comprises a rod attached to the piston and extending through one end of the cylinder. In both situations, fluid is introduced into a first side of the cylinder to move the piston in one direction while fluid on the second side of the piston is exhausted to the environment. To reverse directions of the piston, fluid is introduced on the second side of the piston and exhausted from the first side.
Due, in part, to the success of fluid operated actuators, there has been an attempt to increase the potential environments in which the actuators can be utilized. For example, there is a desire to utilize fluid operated actuators in sanitary environments, such as food and beverage factories; however, due to the external surfaces, the exterior of fluid operated actuators typically cannot be properly cleaned between or during use. Therefore, there has been an attempt to provide a fluid operated actuator with a generally smooth exterior surface. In other words, the exterior surface is generally free of sharp changes or protruding ribs or crevices that can collect fluid and bacteria. Prior art fluid operated actuators have been limited in how the various components are manufactured. This is because creating a smooth exterior surface has been problematic in the past when the fluid operated actuator is formed by a pressure die-cast process. This is because as is generally known in pressure die-cast processes, there is a desire to provide a substantially equal wall thickness throughout a particular part. However, due to the various internal configurations and passages, an equal wall thickness is difficult to obtain while providing a smooth exterior surface. Further, typical die-cast parts comprise a solid structure resulting in a relatively heavy and expensive component.
In addition, the fluid supply to/from the fluid operated actuator is typically controlled by a valve that is separate and sometimes remote from the fluid operated actuator. As a result, a series of complex external piping and electrical wiring is often required. The piping is typically required to provide a fluid communication path for actuating the fluid operated actuator. The wiring is typically required for various sensors that may be provided on the fluid operated actuator. Not only is the external piping and wiring expensive, but also it is difficult to keep properly cleaned. Therefore, there is a desire to provide a fluid operated actuator that includes an integrated valve that can be easily removed and replaced depending on the particular application. Further, there is a need to provide a pilot valve that can control the integrated valve without requiring excessive piping and electrical connections.
Another problem with prior art actuators is the requirement to provide an individual seal for each fluid passage that is provided in the fluid operated actuator. Each component may have various ports, which typically require individual seals. However, providing individual seals can become costly as the number of components provided in a fluid operated actuator increases. Therefore, there is a need to reduce the cost and complexity associated with providing a fluid tight fluid operated actuator.
The present invention overcomes these and other problems and an advance in the art is achieved. The present invention provides a fluid operated actuator with an integrated valve. The present invention provides an integrated pilot control and sensing module. Further, the present invention provides end caps that are formed using a die-cast process while comprising a smooth exterior surface. The present invention also provides a multiple lip seal that is capable of providing a fluid tight seal between various ports thereby reducing the total number of separate sealing members. The various features of the present invention may be combined in a single actuator or may be utilized individually in prior art actuators.